Resistive switching devices having a switching layer and an intermediate electrode layer and methods of formation thereof

Abstract

In one embodiment of the present invention, a resistive switching device includes a first electrode disposed over a substrate and coupled to a first potential node, a switching layer disposed over the first electrode, a conductive amorphous layer disposed over the switching layer, and a second electrode disposed on the conductive amorphous layer and coupled to a second potential node.

What is claimed is: 
     
       1. A resistive switching device comprising:
 a first electrode coupled to a first potential node, the first electrode disposed over a substrate; 
 a second electrode coupled to a second potential node; 
 a switching layer disposed between the first electrode and the second electrode and contacting the first electrode, wherein the switching layer comprises a first impedance in a first state of the resistive switching device and a second impedance in a second state of the resistive switching device, the second state being different from the first state; and 
 a conductive amorphous layer disposed between the switching layer and the second electrode and contacting the switching layer, wherein the conductive amorphous layer comprises a substantially same impedance in the first state and the second state, wherein the second electrode is disposed over and contacts the conductive amorphous layer, and wherein the conductive amorphous layer comprises tellurium or selenium. 
 
     
     
       2. The device of  claim 1 , wherein the conductive amorphous layer comprises tellurium and a metal element. 
     
     
       3. The device of  claim 2 , wherein the switching layer comprises gadolinium oxide, aluminum oxide, hafnium oxide, zirconium oxide, silicon oxide, or mixtures thereof. 
     
     
       4. The device of  claim 2 , wherein the metal element comprises a group IV element comprising titanium, zirconium, and/or hafnium. 
     
     
       5. The device of  claim 4 , wherein the ratio of the number of group IV element atoms to the number of tellurium atoms in the conductive amorphous layer is between 0.5:1 to 3:1. 
     
     
       6. The device of  claim 1 , wherein the conductive amorphous layer comprises less than 0.01% of copper and silver, wherein the second electrode comprises less than 5% of copper and silver, wherein the switching layer comprises less than 0.01% of copper and silver. 
     
     
       7. The device of  claim 1 , wherein the first electrode comprises tungsten and/or tantalum and wherein the second electrode comprises titanium nitride. 
     
     
       8. The device of  claim 1 , wherein the second electrode comprises a diffusion barrier to copper, silver, gold, zinc, and tellurium. 
     
     
       9. The device of  claim 8 , further comprising a third electrode disposed over and contacting the second electrode. 
     
     
       10. The device of  claim 1 , wherein the conductive amorphous layer comprises selenium and a group IV element, wherein the group IV element comprises titanium, zirconium, and/or hafnium. 
     
     
       11. The device of  claim 1 , further comprising:
 another switching layer disposed between the first electrode and the second electrode; and 
 another conductive amorphous layer disposed between the another switching layer and the second electrode and contacting the another switching layer and the second electrode, wherein the another conductive amorphous layer comprises tellurium or selenium. 
 
     
     
       12. The device of  claim 1 , wherein the first electrode and the second electrode comprise tantalum. 
     
     
       13. A resistive switching device comprising:
 a first electrode coupled to a first potential node, the first electrode disposed over a substrate; 
 a oxide switching layer disposed over the first electrode, wherein the oxide switching layer comprises less than 0.01% of copper and silver, wherein the oxide switching layer comprises a first impedance in a first state of the resistive switching device and a second impedance in a second state of the resistive switching device, the second state being different from the first state; 
 a second electrode disposed on the oxide switching layer and coupled to a second potential node; and 
 an interface between the oxide switching layer and the second electrode, wherein the interface comprises tellurium, wherein the second electrode comprises less than 5% of copper and silver. 
 
     
     
       14. The device of  claim 13 , wherein the second electrode comprises a diffusion barrier for tellurium. 
     
     
       15. The device of  claim 13 , wherein the first electrode comprises tungsten and/or tantalum, and wherein the oxide switching layer comprises gadolinium oxide, aluminum oxide, hafnium oxide, zirconium oxide, silicon oxide, or mixtures thereof. 
     
     
       16. The device of  claim 13 , wherein the second electrode comprises titanium nitride. 
     
     
       17. The device of  claim 16 , wherein the second electrode comprises a titanium layer at the interface. 
     
     
       18. The device of  claim 13 , wherein the second electrode comprises tellurium. 
     
     
       19. The device of  claim 13 , further comprising:
 another oxide switching layer disposed over the first electrode, wherein the another oxide switching layer comprises less than 0.01% of copper and silver, wherein the second electrode is disposed over the another oxide switching layer; and 
 another interface between the another oxide switching layer and the second electrode, wherein the another interface comprises tellurium. 
 
     
     
       20. The device of  claim 13 , wherein the second electrode comprises tantalum. 
     
     
       21. The device of  claim 13 , wherein the interface comprises a conductive alloy between tellurium and a metal excluding copper and silver. 
     
     
       22. A metal oxide resistive switching device comprising:
 a first electrode coupled to a first potential node; 
 a metal oxide layer disposed over the first electrode, wherein the metal oxide layer comprises a first impedance in a first state of the metal oxide resistive switching device and a second impedance in a second state of the metal oxide resistive switching device, the second state being different from the first state; 
 a tellurium layer disposed over and contacting the metal oxide layer, wherein the tellurium layer comprises less than 0.01% of copper and silver; and 
 a second electrode disposed over and contacting the tellurium layer, the second electrode coupled to a second potential node, wherein the second electrode comprises less than 5% of copper and silver. 
 
     
     
       23. The device of  claim 22 , wherein the tellurium layer comprises titanium, zirconium, and/or hafnium. 
     
     
       24. The device of  claim 22 , wherein the total amount of tellurium by atomic percent in the tellurium layer is 25% to 70%. 
     
     
       25. The device of  claim 22 , further comprising a third electrode disposed over and contacting the second electrode. 
     
     
       26. The device of  claim 22 , wherein the tellurium layer is amorphous. 
     
     
       27. The device of  claim 22 , wherein the second electrode is a diffusion barrier to copper and silver. 
     
     
       28. The device of  claim 22 , further comprising:
 another metal oxide layer disposed over the first electrode; and 
 another tellurium layer disposed over and contacting the another metal oxide layer, wherein the another tellurium layer comprises less than 0.01% of copper and silver. 
 
     
     
       29. A resistive switching device comprising:
 a first electrode coupled to a first potential node, the first electrode disposed over a substrate; 
 a oxide switching layer disposed over the first electrode, wherein the oxide switching layer comprises less than 0.01% of copper and silver; 
 a second electrode disposed on the oxide switching layer and coupled to a second potential node; 
 an interface between the oxide switching layer and the second electrode, wherein the interface comprises tellurium, wherein the second electrode comprises less than 5% of copper and silver; 
 another oxide switching layer disposed over the first electrode, wherein the another oxide switching layer comprises less than 0.01% of copper and silver, wherein the second electrode is disposed over the another oxide switching layer; and 
 another interface between the another oxide switching layer and the second electrode, wherein the another interface comprises tellurium. 
 
     
     
       30. A metal oxide resistive switching device comprising:
 a first electrode coupled to a first potential node; 
 a metal oxide layer disposed over the first electrode; 
 a tellurium layer disposed over and contacting the metal oxide layer, wherein the tellurium layer comprises less than 0.01% of copper and silver; 
 a second electrode disposed over and contacting the tellurium layer, the second electrode coupled to a second potential node, wherein the second electrode comprises less than 5% of copper and silver; 
 another metal oxide layer disposed over the first electrode; and 
 another tellurium layer disposed over and contacting the another metal oxide layer, wherein the another tellurium layer comprises less than 0.01% of copper and silver.